#include <iostream>
using namespace std;
long long a[10000005];//f[i]表示最大值；
long long f[40000005];
long long lazym[40000005];
long long lazyadd[40000005];
long long inf = -2000000000;
void up(int i) {
	f[i] = max(f[i * 2], f[i * 2 + 1]);
}
void build(int l, int r, int i) {
	lazym[i] = inf;
	lazyadd[i] = 0;
	if (l == r) {
		f[i] = a[l];
		return;
	}
	int mid = (l + r) / 2;
	build(l, mid, i * 2);
	build(mid + 1, r, i * 2 + 1);
	up(i);
	return;
}
void down(int i) {//负责蓝信息的下发
	if (lazym[i]!=inf) {
		lazyadd[i * 2] = 0;
		lazyadd[i * 2 + 1] = 0;
		lazym[i * 2] = lazym[i];
		lazym[i * 2 + 1] = lazym[i];
		f[i * 2] = lazym[i];
		f[i * 2 + 1] = lazym[i];
		lazym[i] = inf;
	}
	if (lazyadd[i] != 0) {
		lazyadd[i * 2] += lazyadd[i];
		lazyadd[i * 2 + 1] += lazyadd[i];
		f[i * 2] += lazyadd[i];
		f[i * 2 + 1] += lazyadd[i];
		lazyadd[i] = 0;
	}
}
void modify(int jobl, int jobr, int l, int r, int i, int x) {
	if (l >= jobl && r <= jobr) {
		f[i] = x;
		lazym[i] = x;
		lazyadd[i] = 0;
	}
	else {
		int mid = (l + r) / 2;
		down(i);
		if (mid >= jobl) {
			modify(jobl, jobr, l, mid, i * 2, x);
		}
		if (mid < jobr) {
			modify(jobl, jobr, mid + 1, r, i * 2 + 1, x);
		}
		up(i);
	}
}
void add(int jobl, int jobr, int l, int r, int i, int x) {
	if (l >= jobl && r <= jobr) {
		f[i] += x;
		lazyadd[i] += x;
		return;
	}
	else {
		int mid = (l + r) / 2;
		down(i);
		if (mid >= jobl) {
			add(jobl, jobr, l, mid, i * 2, x);
		}
		if (mid < jobr) {
			add(jobl,jobr, mid + 1, r, i * 2 + 1, x);
		}
		up(i);
	}
}
long long querymax(int jobl, int jobr, int l, int r, int i) {
	if (l >= jobl && r <= jobr) {
		return f[i];
	}
	else {
		long long ans = inf;
		int mid = (l + r) / 2;
		down(i);
		if (mid >= jobl) {
			ans = max(ans, querymax(jobl, jobr, l, mid, i * 2));
		}
		if (mid < jobr) {
			ans = max(ans, querymax(jobl, jobr, mid + 1, r, i * 2 + 1));
		}
		up(i);
		return ans;
	}
}
int main()
{
	int n, q;
	cin >> n >> q;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
	}
	build(1, n, 1);
	int op, l, r, x;
	for (int i = 1; i <= q; i++) {
		cin >> op;
		if (op == 1) {
			cin >> l >> r >> x;
			modify(l, r, 1, n, 1, x);
		}
		else if (op == 2) {
			cin >> l >> r >> x;
			add(l, r, 1, n, 1, x);
		}
		else if (op == 3) {
			cin >> l >> r;
			int maxnum = querymax(l, r, 1, n, 1);
			cout << maxnum << endl;
		}
	}
}